The Existence of a Microbiologically Inactive “Folic Acid”-Like Material Possessing Vitamin Activity in the Rat

Abstract

In order to produce the syndrome of “folic acid” (FA) deficiency in the rat it is necessary to include much larger amounts of succinylsulfathiazole (SST) in diets of powdered milk than in highly purified diets of comparable FA content. The deficiency resulting from the feeding of diets composed of powdered milk and large amounts (10 or 20%) of SST is characterized by a failure in growth, the attainment of low hepatic levels of FA, a low total leucocyte count, and a low percentage of circulating grannlocytes. Large amounts of FA are eliminated in the feces of rats fed exclusively on powdered milk. This fecal elimination of FA is reduced by feeding SST, but a syndrome of FA deficiency can exist in the presence of a considerable fecal elimination of the vitamin. By the use of liver digestion techniques or by the use of a more highly purified enzyme capable of releasing FA from a non-microbiologically active complex, it was possible to show that powdered milk contains significant amounts of “potential FA.” It is concluded that the “potential FA” of milk, unavailable as such to microorganisms, is utilizable by the rat. The existence of such “potential FA” offers an explanation for the apparent discrepancy between the FA content of milk powder found microbiologically and that indicated by the results of growth experiments in rats.